During recent years, the machine vending of various goods has expanded considerably to the extent that now many vending machines are placed in outside locations that are unattended and unlocked, at least most of the time. The temptation for burglary and simple vandalism is a considerable problem in the industry to such an extent that several burglar alarms or tampering warning systems have been proposed. Although burglary of the machines and larceny of either the money or goods from the machine is a problem, a much greater problem is the damage to the vending machine itself which occurs during the break in, and which causes a considerably greater economic loss than the amount of goods or money which is taken from the machine at any particular time.
The general approach of the vandal or the unsophisticated burglar is to try to pry open the door with a crow bar or other lever means. Most of the alarms proposed to date are triggered by a switch at either the bottom or top of the door which is set off when the door separates from the cabinet edge. However, if the burglar or vandal is attempting to pry open the door at a point below the latch, and if the alarm switch is above the latch, the alarm may not be triggered at all, or else by the time the alarm is triggered, several hundred dollars worth of damage to the machine and door may have occurred. It is not sufficient to provide an alarm that requires opening of the door at all points around the edge to insure triggering of the alarm, because by that time the damage has been done.
Other problems include the means by which the alarm circuit is armed at the outset. Generally, the alarm circuit is armed by a separate key which makes arming of circuit not only time consuming, but sometimes possibly overlooked by the attendant. Also, alarms, even though fired, may be quickly shut off once the vandal or burglar gains access to the inside of the cabinet.